Aim: The aim of the study was to analyze and compare the manual cephalometric tracings with computerized cephalometric tracings using Burstone hard tissue analysis and McNamara analysis. Materials and Methods: Conventional lateral cephalograms of 20 subjects were obtained and manually traced. The radiographs were subsequently scanned and digitized using Dolphin Imaging software version 11.7. McNamara analysis and Burstone hard tissue analysis were performed by both conventional and digital method. No differentiations were made for age or gender. Data were subjected to statistical analysis. Statistical analysis was undertaken using SPSS 17.0 version (Chicago, Illinois, USA) statistical software program. A paired t-test was used to detect differences between the manual and digital methods. Statistical significance was set at the P < 0.05 level of confidence. Results: (A) From Burstone analysis variables N-Pg II Hp show statistically very significant difference, and ANS-N, U1-NF, N-B II Hp, L1-Mp, and Go-Pg shows the statistically significant difference. (B) From McNamara analysis variables Nasolabial angle and L1-APog show statistically significant differences and the Mandibular length shows the statistically very significant difference. Conclusion: According to this study, is reasonable to conclude that the manual and digital tracings show the statistically significant difference.

For more than seven decades, cephalometry has been one of the main diagnostic tools available to the orthodontist. Cephalometric norms were published by prominent clinicians and researchers, and are used for diagnosis, treatment progress, posttreatment evaluation, and research. In orthodontics, cephalograms are the crucial diagnostic component. It is essential for correct treatment assessment and later for the evaluation of the therapy. The cephalometric analysis can be performed manually or by software. The digital evaluation of cephalometric analysis supplemented with two-dimensional profile photo of the patient provides an overview of changes caused by the therapy. [1]

The conventional cephalometric analysis is performed by tracing radiographic landmarks on acetate overlays and measuring linear and angular values. However, despite its widespread use in orthodontics, the technique is time-consuming and has several drawbacks, including a high-risk of error in tracing, landmark identification, and measurement. Cephalometric errors can be divided into those related to the acquisition, identification, and technical measurement. Reproducibility of measurements by the operator is also a significant factor in determining the accuracy of any method of analysis. [2]

The use of computers in treatment planning is expected to reduce the incidence of personal errors due to operator fatigue and provide standardized, fast, and effective evaluation with a high rate of reproducibility. With the rapid evolution of computer radiography, digital tracing has slowly replaced the manual tracing methods. The use of both digital radiography and conversion of manual film to a digital format offers several advantages - it is easy to use, allows several analyses to be performed at a time, promises convenience when generating treatment predictions, takes up less storage space, allows superimposition of images, provides the option to manipulate the size, and contrast of the image; and provides the ability to archive and improve access to images to overcome the problem of film deterioration, which has been a major source of informations loss in craniofacial biology. [3]

The concept of the digital radiographic image refers to the image obtained from X-rays incidence and displayed on the computer. It can be achieved by two different ways: Through systems with or without the use of radiographic films. These methods can also be called indirect or direct method. In the direct method, the image is captured directly through a charged coupled device eliminating the use of radiographic film and darkroom. In the indirect method, also called hybrid system, a conventional radiography is recorded by a video camera or scanner and converted into digital format in a computer through a software program. Digital radiography offers several advantages since it allows improved the assessment of the image by using graphic and image processing software, which can reverse color scale, enhance specific areas, provide texture manipulation, and others. According to manufacturers, it also presents approximately 80% radiation dose reduction compared to conventional radiographies. [4]

However, still some orthodontist prefers manual method than the use of computers. One of the reasons is the inevitability of the financial investments in the software and feels that the conventional method is the adequate technique. Hence, the present study was carried out in order to find which method is superior in terms of accuracy and adequacy.

Hence, the present study was undertaken to evaluate the significant difference between skeletal, dental variables by two methods of tracing: That is, manual tracing and computerized cephalometric tracing.

Materials and Methods

The comparison is based on an evaluation of 20 cephalograms of patients with Class I molar relation and with a straight profile from the archives of the outpatient clinic of the Department of Orthodontics and Dentofacial Orthopedics. No differentiations were made for age or gender. The patients were selected with the following criteria:

Good quality radiographs without any artifacts that might interfere with the location of the anatomical landmarks.

Patient biting in occlusion (maximum intercuspation).

Permanent dentition with no missing teeth.

No excess soft tissue (as determined from the radiographs) that could interfere with locating anatomical points.

No history of previous orthodontic treatment.

No history of trauma, plastic or orthognathic surgery or no obvious facial asymmetry.

The overall goal of the study was to compare the conventional method of manual tracing with a computer method, where 20 lateral cephalograms were scanned and analyzed using Dolphin Imaging software version 11.7.5.55. Our main objective was to evaluate the significant difference between both series of values resulting from manual and digital processing. Two analysis Burstone hard tissue and McNamara analysis were done. All parameters of the analysis were obtained both manually and with the digital method.

The cephalometric analysis was done by two methods:

Manual method.

Digital method.

Manual methods

After sample selection, a single examiner performed the cephalometric tracings manually. These were performed over a period of 5 days and then the cephalometric measurements were taken. A sheet of leads acetate tracing paper measuring 8 × 10-in and 0.003-in thickness was used. For bilateral structures and double images, the mid-point was chosen by construction. The tracings were done on a view box with the tracing paper securely positioned over the radiograph with a masking tape. After completion of the cephalograms using the manual methods, the following cephalometric landmarks were traced and illustrated in [Figure 1]. Point S (Sella); Point N (Nasion); Point ANS (anterior nasal spine); Point PNS (Posterior Nasal Spine); Point Po (Porion); Point Or (Orbitale); Point A (Subspinale); Point B (Supramentale); Point Pog (Pogonion); Point Me (Menton); Point Go (Gonion); Point Gn (Gnathion); Point Co (Condylion); Point Articulare (Ar); Point Pn (Nose tip); Point Si (Upper lip); and Point Sn (Subnasale). Once the landmarks had been traced, the lines and planes, depicted in [Figure 1], could be obtained.

The 20 cephalometric radiographs were scanned into digital format using an Epson version 700 scanners and exported to the Dolphin Imaging ® 11.7.5.55 software (Dolphin Imaging and Management Solutions, Chatsworth, Los Angeles, California, USA). The images were converted to JPEG format and saved with maximum quality with the Dolphin Imaging 11.7.5.55 program. The file size of the final image was about 200 Kb, with 200 dpi resolution. Before implementing the digital tracings, it was essential to determine the start and end points of the ruler (100 mm) with the purpose of rendering the actual size of each radiographic image. The program illustrates all points and their tracing sequence and allows users to magnify any specific areas [Figure 2].

Evaluation of statistical differences of the cephalometric values by the manual and digital methods was performed by applying paired t-test. A P = 0.05 was used as the minimal level of statistical significance. All the data analysis was done by using SPSS version 17.0 (Chicago, Illinois, USA) statistical analysis software.

Cephalometry has contributed countless benefits to scientific research and the development of Orthodontics. A subsidiary task to the research objectives was to evaluate the most dissimilar cephalometric variables between manual and digital series.

The manual method is not only time-consuming but also allows more measurement errors caused by doctors. The reproducibility of cephalometric points in conventional method on paper in comparison to the analysis of digital image was controversial for a long time. The complicated process to obtain a digital record of X-ray, loss of data during digitization resulting in reduced quality of the image or complicated and not sufficiently tested software analysis disputable in the past. [1] Nowadays due to the technology advancement and necessity of data mobility the manual method is becoming a handicap. Nowadays, digitizing X-rays has become the preferred method to perform cephalometric measurements. As technology evolves, it becomes increasingly easier for professionals to adapt to the many routine tasks of clinical practice. [5]

Landmark identification from digital images can be affected by several factors such as spatial and contrast resolution of the display device, background luminance level and luminance range of the display system, brightness uniformity, extraneous light in the reading room, displayed field size, viewing distance magnification functions, and user interface. Linear measurements may be affected by the inclination of the reference line, and angular measurements cannot indicate correctly the jaw relationship in the case of extreme facial divergence. [6]

The cephalometric radiographs used in this study were randomly selected and represented the quality of daily routine work. The variables used in this study were commonly used cephalometric variables for orthodontic diagnosis, treatment planning and evaluation of treatment results. Burstone hard tissue analysis is commonly used for orthognathic surgical planning, and McNamara analysis gives an idea of all three parameters: hard tissue, dental variables, and soft tissue variables.

In this study, the analysis of the results obtained when comparing the cephalometric measurements taken in digital and manual tracings revealed values that showed statistically significant differences. These findings support those of Chen etal. [7] and Bruntz etal. [8]

In McNamara analysis, a significant difference was observed in Nasolabial angle and L1-APog. This is because of difficulty in locating Point Pog and because of variability in the sample population, the soft tissue variability is observed. Studies were done by Agarwal etal. [2] had similar problems in locating landmarks gonion, porion, menton, gnathion, pogonion.

In Burstone analysis, a significant difference was observed in ANS-N, U1-NF, N-B II Hp, L1-Mp, Go-Pg, and N-Pg II Hp. This is supported by Murali etal. [6] in which they observed difficulty in locating Point ANS, PNS, and Agarwal etal. [2] had similar problems in locating landmarks gonion, porion, menton, gnathion, pogonion.

Landmark identification is greatly affected by operator experience, which might be as important as the tracing method itself. Because interoperator error has in general been found to be greater than intraoperator error as stated by Sayinsu etal. [9] to minimize the error all measurements in this study were carried out by one examiner.

Conclusion

According to this study and the results achieved by comparing measurements obtained by Burstone and McNamara analysis using manual and digital tracings it is reasonable to conclude that the manual and digital tracings show the statistical significant difference.